A group of hammerhead sharks swims over a sandy bottom with garden eels at Darwin Island.
Photograph: Enric Sala/National Geographic Pristine Seas

Ecuador has created a new marine sanctuary in the Galápagos Islands that will offer protection to the world’s greatest concentration of sharks.

Some 15,000 square miles (38,000 sq km) of the waters around Darwin and Wolf - the most northern islands - will be made off limits to all fishing to conserve the sharks that congregate there and the ecosystem on which they rely.

Several other smaller “no-take” areas have also been created throughout the volcanic archipelago, a biodiversity hotspot around 600 miles (1,000km) off the coast of Ecuador in the Pacific Ocean.

The announcement of the new reserve, which is the same size as Belgium, means that 32% of the waters around Galápagos will now be protected from fishing and other extractive industries. It will be incorporated into the existing 80,000-square mile marine reserve created in 1998.

Until now, small-scale local fishing cooperatives had been allowed to operate in the area, but the government says additional protection is now essential as the habitat has come under increased pressure from global warming and incursions by industrial trawlers and illegal shark fin hunters.

More than 34 different species of shark can be found off the shores of the Galápagos including the largest shark species, the filter-feeding whale shark, the migratory hammerhead shark and the Galápagos shark.

The world’s shark populations are in steep decline. Scientists estimate that about 100 million sharks are killed every year, representing 6-8% of all sharks and far outstripping the ability of populations to recover.

The government hopes the new protection will support a breeding ground that can allow sharks to grow to full size and repopulate the world’s oceans. It hopes the shark sanctuary, together with the existing marine reserve, will strengthen international pressure for ocean conservation, action on shark finning and more ambitious action on climate change.

Environment minister, Daniel Ortega Pacheco, said: “These pristine waters around the Galápagos archipelago are precious not just for Ecuadorians but for the whole balance of our ocean systems. Shark populations in steep decline around the world come here to rest and breed and we want to guarantee complete sanctuary for them.”

The Galápagos Islands were the source of Charles Darwin’s theory of evolution and are seen as a priceless “living laboratory” for scientists.

The combination of cold and warm ocean currents make it one of the most biodiverse marine habitats in the world, supporting almost 3,000 species of fish, invertebrates and marine mammals, endemic seabirds and the world’s only marine iguana. Because of their remote and isolated nature, many species - such as the famous giant tortoises - are found only in the Galápagos and have not changed much since prehistoric times.

Almost 99% of the land area of the islands, which are recognised by Unesco as a world heritage site, are protected as a nature reserve with no habitation allowed and strictly-regulated tourism. The existing marine reserve - one of the world’s largest - was created 18 years ago to protect the unique habitat from industrial fishing.

At the launch of the newest reserve, Ecuador’s president, Rafael Correa, will say: “The establishment of this marine sanctuary represents a major breakthrough, not least because it hosts the largest biomass of sharks in the world, which is an indicator of the pristine condition of the site as well as the importance of conservation.”

The scheme has been supported by the National Geographic Foundation, which has offered compensation to the local fishing cooperatives. The government says evidence from other no-take zones around the world shows there is net benefit for local fishermen through an increase in fish numbers outside the protected zone.

A 2015 economic study calculated that the tourism value of a shark over its lifetime in the Galápagos is US$5.4m (£3.75,) while a dead shark brings in less than US$200.